1. Field of the Invention
This invention relates to a magnetic tape recording playback device for recording digital data on a magnetic tape and reproducing the data recorded on the tape. More particularly, it relates to a magnetic tape recording/playback device in which, when recording data on the magnetic tape, the recorded data is monitored so that data recording may be made while the recording state is checked simultaneously.
2. Description of the Related Art
A magnetic recording/playback device, known as R-DAT, in which rotary heads, each including a rotary drum fitted with a magnetic head, rotate so that the magnetic head maintains sliding contact with the magnetic tape with a tilt relative to the longitudinal direction of the magnetic tape for recording digital signals has been developed. The magnetic head records data onto the magnetic tape, and in which data recorded in this manner on the tape can be reproduced, and put to practical application.
The rotary heads loaded on the R-DAT are comprised of two magnetic heads which may be employed both for recording and for playback and which are arranged with a spacing of approximately 180.degree. relative to each other. The relative position between the magnetic tape and the magnetic heads is set so that the locus of movement of each magnetic head is inclined with respect to the longitudinal direction of the magnetic tape.
Such R-DAT is presently employed not only for recording digital audio data on the magnetic tape or reproducing the recorded audio data from the magnetic tape, but also for a back-up external storage device of a computer control program or data, referred to hereinafter as computer data.
Especially, in view of the demand for assuring positive data storage, assuring the back-up of computer data is needed to provide a method of checking whether the computer data has been correctly recorded on the magnetic tape.
In a conventional recording/playback device for a magnetic tape, as disclosed in JP UM KOKOKU Publication No. 4-18081 (1992), first and second recording heads for recording digital data on a magnetic tape are arranged on a rotary drum at an angular distance of 180.degree. relative to each other, and a first playback head for reading the data recorded on the magnetic tape by the first recording head is arranged at a position delayed 270.degree. from the first recording head, while a second playback head for reading the data recorded on the magnetic tape by the second recording head is arranged at a position delayed 270.degree. from the second recording head. A playback head is arranged at a height position lower by 1.5 Tp+(Tw-Tp)/2 lower than the recording head, where Tp is the track pitch of the recording format recorded by the recording heads and Tw is the head width. Data recording is made as the data recorded by the recording heads are monitored by the playback heads for confining the recording state.
Meanwhile, an external storage device for assuring computer data back-up currently in use is a flexible disc rotatably accommodated in a disc cartridge. The recording format for such flexible disc is not standardized, and one of a variety of recording formats may be selected depending on the data volume desired to be stored.
A similar concept is employed for magnetic tapes adapted for R-DAT, such that there are two recording formats for storage of computer data, namely a DDS format with an ordinary track pitch and a DDS-2 format with a narrow track pitch. That is, there are two different types of magnetic tapes as far as the recording format is concerned.
Since only one type of recording format may be applied for conventional recording/playback device using magnetic tapes, it becomes necessary to provide different rotary heads for the different recording formats. Although it is possible to increase the number of magnetic heads by correspondingly increasing the number of channels of the rotary transformers to cope with different recording formats by a sole rotary head, it becomes necessary in such case to find an optimum value of the head width of the playback heads from the electro-magnetic conversion characteristics and automatic track following (ATF) characteristics, by reason of the necessity of having the recording track correctly followed by the playback heads, with the consequence that the designing of the rotary heads become excessively complicated.
Besides, since the rotary drum diameter is as small as 30 mm and hence limitations are imposed on the number of the magnetic heads and the rotary transformers that may be mounted on the rotary drum, and manufacture difficulties, such as drastic changes in the rotary drum construction, are incurred if the numbers of the playback heads or the rotary transformers are to be increased, while manufacture costs are also raised.